Layered silicate materials (phyllosilicates) can be exfoliated by having monomers sorbed or intercalate between the adjacent platelets of the silicate. Sufficient monomer is sorbed to expand the adjacent platelets, and the intercalate is then easily exfoliated into individual platelets. The exfoliation can occur by the application of a shear force. Monomeric ethers and esters, as well as those with hydroxyl groups can be sorbed directly between the phyllosilicate layers, as shown in U.S. Pat. Nos. 6,461,423 and 6,287,634.
US patent application Ser. No. 2005/0137288, and U.S. Pat. No. 6,906,127 describe a method for forming exfoliates by intercalating a layered silicate material with an oligomer or pre-polymer, and then polymerizing the monomer while in contact with the clay to form a nano-clay modified polyamide or nylon. The amine functionality is protonated for ion-exchange with interlayer cations to bond the intercalant to the phyllosilicate platelet. The intercalated silicate materials are then compounded into a polymer matrix to achieve excellent thermal stability.
Hasegawa et al. showed that oligomeric, i.e. low molecular weight PP-MAH [J. Appl. Polym. Sci. 1998, 67, 87-92] significantly improved the exfoliation of clay platelets with concomitant increases in PP mechanical properties when compounded by extrusion.
U.S. Pat. No. 6,462,122 and U.S. Pat. No. 6,632,868 describe the use of a maleic anhydride modified polypropylene in both the intercalation of phyllosilicates, and in the polymer matrix to aid dispersion.
The use of copolymers as compatibilizing aids between a polymer matrix and different additives are well known. The copolymers tend to increase system miscibility by reducing interfacial tension and promoting adhesion at the interface.
A copolymer having a non-olefinic hydrophobic moiety, and a hydrophilic alpha-beta unsaturated carbonyl moiety has now been found to both act as an intercalation agent for phyllosilicates, and also to act as a compatibilizer between nanoclays, impact modifiers, and thermoplastic matrices.